Mercury rules 12th and 3rd house is in 8th house in Aquarius

As a Jyotish astrologer, I can tell you that having Mercury in the 8th house in Aquarius sign can have several effects on an individual.

Firstly, this placement indicates a sharp intellect and excellent analytical skills. The individual is likely to have a keen interest in research, investigation, and solving complex problems related to various aspects of life.

However, this placement may also indicate a tendency towards being secretive, cunning, and manipulative. The person may also have a difficulty in letting go of their past and may hold grudges for a long time.

The individual's communication style may be unconventional and they may have unique ideas and beliefs that set them apart from others. There may also be a significant interest in supernatural and occult knowledge.

Overall, the placement of Mercury in the 8th house in Aquarius sign can have both positive and negative effects on the individual's life, but these effects can be mitigated through guidance from a qualified astrologer.